So, it is responsible for invoking /usr/bin/click hook run-system. According to its man-page, click is a

package management tool for Ubuntu Touch

and the parameters hook run-system mean

Run all system-level hooks for all installed Click packages. This is useful when starting up from images with preinstalled packages which may not have had their system-level hooks run properly when building the image.

Concluding, if you don't run Ubuntu Touch, you may disable the service via sudo systemctl disable click-system-hooks.service or remove click completely from your system.

For me, I suspect, it came with the package unity8-desktop-session which indirectly depends on click and must not be installed without.